3.7 Merge window part 2

By Jonathan Corbet
October 10, 2012

As of this writing, Linus has pulled 9,167 non-merge changesets into the mainline for the 3.7 merge window; that's just over 3,600 changes since last week's summary. As predicted, the merge rate has slowed a bit as Linus found better things to do with his time. Still, it is shaping up to be an active development cycle.

User-visible changes since last week include:

The kernel's firmware loader will now attempt to load files directly from user space without involving udev. The firmware path is currently wired to a few alternatives under /lib/firmware; the plan is to make things more flexible in the future.
The epoll_ctl() system call supports a new EPOLL_CTL_DISABLE operation to disable polling on a specific file descriptor.
The Xen paravirtualization mechanism is now supported on the ARM architecture.
The tools directory contains a new "trace agent" utility; it uses virtio to move trace data from a guest system to a host in an efficient manner. Also added to tools is acpidump, which can dump a system's ACPI tables to a text file.
Online resizing of ext4 filesystems that use the metablock group (meta_bg) or 64-bit block number features is now supported.
The UBI translation layer for flash-based storage devices has gained an experimental "fastmap" capability. The fastmap caches erase block mappings, eliminating the need to scan the device at mount time.
The Btrfs filesystem has gained the ability to perform hole punching with the fallocate() system call.
New hardware support includes:
- Systems and processors: Freescale P5040DS reference boards, Freescale / iVeia P1022RDK reference boards, and MIPS Technologies SEAD3 evaluation boards.
- Audio: Wolfson Bells boards, Wolfson WM0010 digital signal processors, TI SoC based boards with twl4030 codecs, C-Media CMI8328-based sound cards, and Dialog DA9055 audio codecs.
- Crypto: IBM 842 Power7 compression accelerators.
- Graphics: Renesas SH Mobile LCD controllers.
- Miscellaneous: ST-Ericsson STE Modem devices, Maxim MAX8907 power management ICs, Dialog Semiconductor DA9055 PMICs, Texas Instruments LP8788 power management units, Texas Instruments TPS65217 backlight controllers, TI LM3630 and LM3639 backlight controllers, Dallas DS2404 RTC chips, Freescale SNVS RTC modules, TI TPS65910 RTC chips, RICOH 5T583 RTC chips, Marvell MVEBU pin control units (and several SoCs using it), Marvell 88PM860x PMICs, LPC32x SLC and MLC NAND controllers, and TI EDMA controllers.
- Video4Linux2: Syntek STK1160 USB audio/video bridges, TechnoTrend USB infrared receivers, Nokia N900 (RX51) IR transmitters, Chips&Media Coda multi-standard codecs, FCI FC2580 silicon tuners, Analog Devices ADV7604 decoders, Analog Devices AD9389B encoders, Samsung Exynos G-Scaler image processors, Samsung S5K4ECGX sensors, and Elonics E4000 silicon tuners.

Changes visible to kernel developers include:

The precursors for the user-space API header file split have been merged. These create include/uapi directories meant to hold header files containing the definitions of data types visible to user space. Actually splitting those definitions out is a lengthy patch set that looks to be only partially merged in 3.7; the rest will have to wait for the 3.8 cycle.
The core of the Nouveau driver for NVIDIA chipsets has been torn out and rewritten. The developers understand the target hardware much better than they did when Nouveau started; the code has now been reworked to match that understanding.
The Video4Linux2 subsystem tree has been massively reorganized; driver source files are now organized by bus type. Most files have moved, so developers working in this area will need to retrain their fingers for the new locations. There is also a new, rewritten DVB USB core; a number of drivers have been converted to this new code.
The ALSA sound driver subsystem has added a new API for the management of audio channels; see Documentation/sound/alsa/Channel-Mapping-API.txt for details.
The red-black tree implementation has been substantially reworked. It now implements both interval trees and priority trees; the older kernel "prio tree" implementation has been displaced by this work and removed.

Linus had raised the possibility of extending the merge window if his travels got in the way of pulling changes into the mainline. The changeset count thus far, though, suggests that there has been no problem with merging, so chances are that the merge window will close on schedule around October 14.